TPI conversion 95 GMC truck

[Hardrock]

Hi Dave.
Thanks for the reply.

Basically, I figured swapping to the '730 would give me the option to tune with Dynamic-efi.
I didn't see any support for the '7427 on their site.
Also wanted 4L60 compatibility, and the '7427 used in the '95 trucks is sort of an oddball from what I've gathered.
PWM converter lockup and shift solenoids with one year only Ohm specs.

I didn't know if that was all in the programming, or built into the PCM itself.

Can I run a '7427 with a 4L60? Like a '95 MT program?
How do I handle TCC lockup?

Mike

[dave w]

There are numerous options.
Using the Moates.net Ostrich 2.0 chip emulator ( http://www.moates.net/ostrich-20-the...eed-p-169.html ) with a '7427 is "On Par" with the Dynamic EFI system. Both the Ostrich 2.0 and Dynamic EFI system use TunerPro RT to upload / download a "Tune File".

Possibly installing PWM delete kit ( https://gmtnation.com/forums/threads...from-tcc.7238/ ) into the 95 4L60E is an option, so the '7427 can use a "Tune File" from a 1994 '7427 non-PWM 4L60E.

I've done several '7427 MPFI conversions, it's an AWESOME low cost option!

dave w

[dave w]

Pic of a 16197427 connected to an Ostrich 2.0.

dave w

DSCN4240.jpg

[Hardrock]

Thanks for the link.
I had no idea TransGo offered a PWM eliminator kit. PWM on a clutch apply circuit never made any sense to me. Just more/faster wear.
That would be a nice upgrade to the '96-newer 4L60e's.

I pretty much need to run the 4L60, though.
One, I have it in front of me, and I know the history on it. Two, the '95 4L60e is in a 2WD configuration, and the truck will end up equipped with 4WD when it's done.

Essentially, what we have under our current shop truck is a well maintained 4WD chassis with upgrades we'd like to keep, but the sheetmetal is toast.
The '95 is a cleaner truck, so it's getting a chassis conversion. the 4L60 comes with the chassis, along with a recent Moog front suspension and a 14 bolt SF rear with a locker. Wheels, tires, brakes, etc. Just too fresh and reliable to abandon.

The two combined will make a respectable shop truck, and a TPI should add a little fun to the mix.

Mike

[dave w]

The 16197427 has programming for TCC only, so using either a 700R4 or 4L60 are options with a 16197427.

The 16197427 usually requires a VSS, 2000 pulses per mile or 2K VSS.

dave w

[1project2many]

It does seem a bit backward to repin for 7730 when 7427 can do the job but I understand KISS in configuration. I have repinned a 7747 truck to 7730 but I think I'd probably build a conversion harness or adapter for this one. I'd leave the trans wiring just in case, just don't connect it to the adapter. 4L60E is much easier to work with than 700R4. When is 4WD install happening? VSS output for 4L60 will come from transfer case after conversion.

I would stay away from 4bbl plus dual TBI for work / shop truck. It's a little work to account for rapid temperature changes in manifold air and resulting fuel puddling when you have dual throttle plates. Tuned port engines were some of the best truck engines never installed in trucks. Pick a gear / tire size to keep engine rpm low and install cam that makes big torque and peak power by 4k rpm and it will run like a BBC.

[Hardrock]

Hi, 1project2many.

I've kind of gathered that the 7427 is the last best OBD1 PCM to use for MPFI. From what I've read, it has functions that even some of the best tuners have yet to uncover. At least that was true a few years back, anyway.

I don't speak "tuner" very well, but my takeaway was, the 7427 does provide a lot more latitude when building a custom tune.
I think I remember reading where it allows isolation of fuel and spark without one automatically influencing the other.
That sounds like a benefit to me.
Lean cruise is something that would interest me also, although I believe it's available with some other PCMs, too.

The move back to the 7730 was my idea to, like you say, K.I.S.S. I know that was GM's answer for SD TPI, and Dynamic-efi offers it already modified.

I know the 7427 would be my first choice when it comes to the 454/4L80e MPFI build, but the shop truck, in my mind, was going to be "bare bones" simple and relatively easy with the 7730. (but again, I'm a newbie. LOL)

4WD will be the final stage of the build.
Right now, the plan is to assemble the 350, drop it in the '95 with the OEM TBI setup and break the cam in.
We have a spare 2WD 4L60 to mock it up and run it with.
Once we're satisfied everything is good to go, we'll put a few miles on it, evaluate it, and then swap on the TPI and start sorting the wiring out.
(think of it as a mobile test bench)

There's a little paint and trim stuff to do, then we'll blow the current truck apart and roll the 4WD chassis under it some weekend.
These trucks are remarkably easy to work on...

I like the idea of tucking the e-trans harness away, just in case I happen to stray across a 4WD 4L60e at a later date.

Quick question. Will the 7427 support ALL GM automatics? 4L60, 4L60e (all years), 4L80e.
Say I happen to find a nice 93-94 4L60e. Am I good with using it?
I know it depends on the bin. but I just don't recall this ECM being used with a '60e and on/off TCC. (93-94)

I'm glad Dave brought up the VSS pulse info. (Thanks, Dave)
Up till now, I've dealt mostly with the 88-94 trucks that had the DRAC from 92-94.
They used a 4K VSS pulse that split to the ECM (I think) and 2K to the speedo, RWAL brakes, and the cruise control module.
This '95 doesn't have a separate DRAC module does it? Didn't see one...

May be another reason to stay with the 7427 if the DRAC function is now handled by the PCM on '95s?

(You guys are slowly talking me into it...Hahaha!)


The twin TBI idea has always interested me since TurboCity offered one way back when. (briefly)
Just a novelty thing, mostly.
That was option #2 if I went with the Vortec heads and intake. Figured a pair of 2.8 V6 TBIs would yield around 670 cfm.
Injectors, I'd have to see what math'd out best.
Just had to figure out how to fab a nice top plate for the Vortec lower plenum. Something on the order of the old Vette Crossfire setup, only inline.
I'm sure twins would present their own set of problems, though.

I think for now, the TPI on the truck heads should work fine for a shop truck.